Highway intersection system



Aug. 27, 1968 J. D. H. DONNAY HIGHWAY INTERSECTION SYSTEM 5 Sheets-Sheet 1 Filed Sept. 17, 1964 MED/AN MINOR D HIGHWAY F J D. H Donnay MED/AN IN VEN TOR.

Aug. 27, 1968 J. D. H. DONNAY HIGHWAY INTERSECTION SYSTEM Filed Sept.

5 Sheets-Sheet 2 J. 0. H. Donnay INVENTOR.

Aug. 27, 1968 J. D. H. DONNAY HIGHWAY INTER SECTION SYSTEM 3 Sheets-Sheet 5 Filed Sept. 17, 1.964

mm? 0 E M R H D. A J M Y R .w W \x E United States Patent 3,399,379 HIGHWAY INTERSECTION SYSTEM Joseph D. H. Donnay, 7200 Charles St., Lutherville, Md. 21093 Filed Sept. 17, 1964, Ser. No. 397,175 2 Claims. (Cl. 340-40) This invention relates generally to highway intersection systems, and more particularly it pertains to an improved major-minor highway crossing system at grade.

It is an object of this invention to provide a road intersection arrangement for continuous, uninterrupted flow of traflic on a major highway without recourse to grade separation.

Another object of this invention is to provide a minor road intersection system at grade with a major road in which minor road trafiic is subjected to less waiting than occasioned with the usual trafiic light arrangements of prior art.

Still another object of this invention is the provision of a system of highway intersection system at grade wherein all crossings are made across an empty road at right angles and all turns strictly directional all with perfect safety and no confusion.

By a new geometric design of road intersection system and appropriate system of time controlled traffic lights this invention requires no overpass construction but is well adapted to a later stage of such construction if desired should the minor highway become of major importance.

This invention further contemplates a diamond arrangement of highway intersection for least interruption of flow of trafiic on a minor highway and no stoppage of trafiic on the intersecting major highway and wherein the land acquisition is reduced to a minimum so that private use of the encompassed land can be continued.

An especially attractive feature of this invention lies in the fact that it is well adapted to urban as well as rural use.

Other objects and attendant advantages of the invention will become more readily apparent and understood from the following detailed specification and accompanying drawings in which:

FIG. 1 is a plan view of a major-minor highway intersection system incorporating features of the invention; and

FIGS. 2, 3, 4, 5 and 6 are traffic-flow patterns illustrating the working of the invention.

With reference now to the details of the drawings, particularly FIG. 1, the new type of intersection system of this invention is intended for any crossing of a major by a minor road. By a new geometric design of the intersection system and by an appropriate system of controlled trafiic lights it achieves the result that the traflic on a major road 10 need not be interrupted to permit the crossing by the traffic of a minor road 12.

A major highway 10, as best shown in FIG. 1 is pro vided with a four-lane highway having a median strip 18, because this situation is likely to be the more common. The Diamond Switch of this invention, however, is applicable to a two-lane highway just as well.

The north-bound traific, in road half 14, at alternate periods, is made to use either the inner road or the outer road 22 to cross the minor highway. The southbound trafiic, in half 16, is similarly made to use either the inner road 24 or the outer road 26, thus permitting minor traflic to cross whichever is unused at the time.

The cycle of operations is shown on FIGS. 2, 3, 4, 5 and 6. The traffic lights or changeable signs are designated by letters.

At time I, as indicated in FIG. 2, the major traffic is using the inner roads 20, 24 and lights A are closed to prevent minor traflic from crossing them. Lights B are open allowing access on the inner roads to the major Patented Aug. 27, 1968 trafiic. Lights C close the outer roads 22 and 26 to major trafli c. Lights D open the way to minor trafiic, which may enter the reservoir roads 28 and 30 between outer and inner roads; lights D also close the outer roads, duplicating the function of lights C, as an added safety; and a permanent sign NO LEFT TURNS is placed at D, to prevent minor trafiic from making a left turn.

Minor traflic that is approaching the intersection, stops at A, minor traffic that is leaving the intersection is free to cross the outer roads and is on its way. At E, some distance ahead of the fork, traflic on the major highway 10 is alerted by the changeable sign SWITCH SIGNALS AHEAD: BEAR LEFT.

When the reservoir roads 28 and 30 are full, or when enough time has elapsed, major trafiic is about to be switched from inner roads to outer roads. The signal at E changes from BEAR LEFT to BEAR RIGHT, shortly before the lights at B and C change, B from green to red and C from red to green.

It is to be noted that both lights B and C have two lights each; one with subscript B for the outer lane of traflic, the other with subscript B for the inner lane, both driving in the same direction on the same highway half. The outer lights B and C are switched a couple of seconds before the inner ones, B C This insures that the traflic of the outer lane will switch to the outer road ahead of the traflic in the inner lane, so that the two lanes will remain separate. We now come to time II, as indicated in FIG. 3.

At time II lights D, which have changed at the same time as the B and C lights, prevent minor trafiic from crossing outer roads 22 and 26 but let major trafiic free to use outer road. Lights A remain red to minor trafiic in reservoir, roads 28, 30, while the lengths of the inner roads 20 and 24 empty of traffic. FIG. 3 shows the last cars leaving the intersection through the inner roads 20 and 24, while the following cars, that have been switched at BC, are progressing along the outer roads 22 and 26, duly protected at D. When the inner roads are completely empty, the lights at A change; this is when time III begins.

At time III as indicated by FIG. 4, the lights at A open the intersection to minor traffic that has been waiting in the reservoir roads 28 and 30. Some cars turn right, some turn left, as shown, onto the empty inner roads; some others go to D, where the red light prevents them from crossing the outer roads 22 and 26. Some newly arrived minor traflic stops at D and waits for the next switch to enter the reservoir.

As soon as the intersection at A is cleared of cars, major traffic may be switched to the inner roads again. The first thing that happens is that the alerting signal at E changes from BEAR RIGHT to BEAR LEFT a couple of seconds before the lights at C and B are reversed. The inner-lane lights C change first, then the outer-lane ones C that is, the inner-lights C turn from green to red as the inner-lights B turn from red to green; then the outer-lights C turn red as the outer-lights B turn green. This precaution is similar to the one described at the end of time I (above). Simultaneously, with the change at the inner lights B and C lights A have changed to stop minor traffic from crossing inner roads. We now enter time IV(a).

At time IV(a) as indicated by FIG. 5, major traffic has just been switched from outer to inner roads. The lights at D remain red to minor traflic; more cars are waiting outside the reservoir at D. A few cars are progressing along the inner roads 20 and 24 after having turned from the minor highway at A. They are on their way to merge with the major traffic on the outer roads 22 and 26 at the far-end fork. A sign MERGING TRAFFIC may be placed at that fork at G if desired.

At time IV(b) as indicated by FIG. 6, major traffic is leaving the intersection on the outer roads 22 and 26. The following cars of major traffic have almost filled the length of the inner roads 20 and 24. Lights D are about to change. At time I, as indicated by FIG. 2, lights D open the way to minor traflic and the cycle repeats.

It will be noted that FIG. 1 further shows an ALL TURNS FROM RIGHT sign F with outer connection road 32 to minor the highway 12. This device also permits the major traffic to make U-turns by joining with the minor traffic and making a left turn at the second A light or D light.

The Diamond Switch combines a large number of advantages. They are listed as follows:

(1) Continuous, uninterrupted flow of traffic on major highway without the necessity to have recourse to grade separation.

(2) Less waiting for minor road traflic than with the usual trafiic lights of the previous art; so, that, even though the crossing requires two or three steps, less total time is spent by minor trafiic at the intersection.

(3) Any 4-leg intersection of the simplest design can be used at the crossing of the inner roads and also at the crossing of the outer roads. All crossings are made at right angles, over an empty road.

(4) Facility and safety of maneuvers: right-turn, through crossing, and left-turn for both highways; U- turn for major highways. (U-turns for minor highway are equally easy and safe should they be required.)

(5) All turns in the intersection are directional.

(6) No special re-education of the public is required; the new system uses familiar signs and is self-explanatory.

(7) Applicability to urban as well as to rural problems.

(8) The Diamond Switch is well adapted to stage development; if an overpass is built later, the outer roads can be used to build a diamond interchange.

(9) The Diamond Switch is flexible in design.

Two examples of geometric design are shown in FIGS. 1 and 2. The critical points are indicated by the letters that have been used to designate the lights. In particular, the storage reservoir enclosed between inner and outer roads bound in one and the same direction can vary in size very considerably. The capacity of the system can be sufficient to accommodate an increasing minor trafiic until such time as the minor highway would itself become a major highway, when the slowing down of its traflic would cease to be acceptable and grade separation would become indicated.

(10) From the point of view of purchase of real estate, the area inside the diamond need not be purchased; present use of the land, for gas stations, restaurants, etc., can be continued. This can be contrasted with the acreage that must be acquired in a cloverleaf interchange, for instance.

(11) Existing ALL-TURNS-TO-THE-RIGHT outer connections may be used, in certain cases, as part of the outer roads, thus keeping down to a minimum the purchase of new right-of-way.

(12) Finally, as to maintenance cost, the system of light signals would be the main item. As the Diamond Switch would normally be installed at a problem intersection that needs correction, a system of trafiic lights would already be in operation there. Although it would have to become more elaborate, it would not have to be a particularly sophisticated system.

As an example the following description shows how the invention can be used, without any outer connections (32, on FIG. 1), in case the major highway is a two-lane 4 highway, instead of a four-lane highway as shown 0 the FIGURES 1 to 6. At B and C, instead of lights that alternately change from green to red, changeable luminous signals are placed that alternately read THROUGH TRAFFIC ONLY and FOR ALL TURNS. The cycle of operations is as follows:

At time I (FIG. 2) B is open to THROUGH TRAF- FIC ONLY and C reads FOR ALL TURNS: motorists who are on the major highway, 14 or 16, and wish to turn right do so at D onto road 12, those who wish to turn left or to make a U-turn turn left at D onto road 28-30 and wait at stoplights A; motorists who approach the intersection on the minor highway will stop at A unless they wish to turn right at D to merge at G.

At time II (FIG. 3) B has changed to read FOR ALL TURNS and C has changed to read THROUGH TRAF- FIC ONLY, while D stops minor trafiic from crossing outer roads 22 and 26. Lights A remain red to minor traffic in reservoir, 28-30, while the inner roads 20 and 24 empty of trafiic. During this time motorists on the major highway who wish to turn left may do so at A, while those who wish to make a U-turn can do it, before they reach the minor highway at A, on half-turn connections (not shown on FIG. 3) between the inner roads 20 and 24.

From then on the cycle proceeds essentially as described above, with the ditferent meaning attached to signals B and C, as already noted.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A highway intersection system comprising a major road consisting of a pair of lane means divided by a median strip, with one of said lane means being for traffic in one direction and the other of said lane means being for traffic in the opposite direction, each of said lane means having a divided section to form an inner road and an outer road, a minor road extending transversely across the divided section of each said lane means of said major road, first means for directing traflic to pass alternately and simultaneously along with the inner road of each said divided section and the outer road of each said divided section to thereby simultaneously free of traffic first each said inner road and then each said outer road, and second means for directing trafiic on said minor road to cross said inner and outer roads of each said divided section when alternately freed of traffic by said (first means and to halt at the intersection with said inner and outer roads when in use by tratfic according to the direction by said first means.

2. The highway intersection system as recited in claim 1 wherein said second means directs trafiic on said minor road to cross the outer road of each said divided section but halts said trafiic at the intersection of said minor road with the inner road of each said divided section until each said inner road is freed of traffic by said first means.

References Cited UNITED STATES PATENTS 4/1960 Soderberg 34040 2/1960 Masten 340--40 

1. A HIGHWAY INTERSECTION SYSTEM COMPRISING A MAJOR ROAD CONSISTING OF A PAIR OF LANE MEANS DIVIDED BY A MEDIAN STRIP, WITH ONE OF SAID LANE MEANS BEING FOR TRAFFIC IN ONE DIRECTION AND THE OTHER OF SAID LANE MEANS BEING FOR TRAFFIC IN THE OPPOSITE DIRECTION, EACH OF SAID LANE MEANS HAVING A DIVIDED SECTION TO FORM AN INNER ROAD AND AN OUTER ROAD, A MINOR ROAD EXTENDING TRANSVERSELY ACROSS THE DIVIDED SECTION OF EACH SAID LANE MEANS OF SAID MAJOR ROAD, FIRST MEANS FOR DIRECTING TRAFFIC TO PASS ALTERNATELY AND SIMULTANEOUSLY ALONG WITH THE INNER ROAD OF EACH SAID DIVIDED SECTION AND THE OUTER ROAD OF EACH SAID DIVIDED SECTION TO THEREBY SIMULTANEOUSLY FREE OF TRAFFIC FIRST EACH SAID INNER ROAD AND THEN EACH SAID OUTER ROAD, AND SECOND MEANS FOR DIRECTING TRAFFIC ON SAID MINOR ROAD TO CROSS SAID INNER AND OUTER ROADS OF EACH SAID DIVIDED SECTION WHEN ALTERNATELY FREED OF TRAFFIC BY SAID FIRST MEANS AND TO HALT AT THE INTERSECTION WITH SAID INNER AND OUTER ROADS WHEN IN USE BY TRAFFIC ACCORDING TO THE DIRECTION BY SAID FIRST MEANS. 